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City of Burlingame Rain Garden
Agenda• Location• Project History and Design• Rain Garden – parking lot• Drainage – storm runoff• Curb Extension – street runoff • Landscaping – California natives• Construction – changes in field• Financing - grant• Interpretive Sign• Lessons Learned
Location – Downtown Burlingame
Project Location
Project History and Design• Existing parking lot with on-street parking behind
shopping district
Public Parking Lot C
Existing ConditionsMultiple driveways
Original landscaping
Poor DrainageStreet runoff collects in gutter
Parking lot drainage ponds
RAIN GARDEN
Reconfigure parking lot with two entrances and 90 degree stalls
Capture 16’ x 160’ area for bioswale
Design for 4’ wide channel at 5”-6” deep
California native landscaping
Irrigation for first few years only, by contractor choice
Two boardwalks for pedestrian access to parking lot
Layout of Redesigned Parking Lot
Rain Garden Photos
STORM DRAINAGE • Captures runoff from commercial buildings and parking lot• 1.32 acres of runoff equals 0.25 cfs for a 30 year event• Designed for 0.43 cfs – almost twice the required C3
guidelines• Overflow to curb for 50 to 100 year storm event
Rain Garden - runoff
Overflow to street
Cross Sections
CURB EXTENSION• Captures Runoff from Street and Parking Stalls• 0.11 acres of runoff at 0.285 cfs – design for 0.33 cfs
exceeding C3 guidelines.• Treats overflows from center cell of garden as well
LANDSCAPING• All plants are California Natives• Includes Rush, Sedges, Carmel Creeper
or Ceanothus, Iris, Barberry and Buckwheat
• Tree specified was native Hackberrys - could not find and used Valley Oaks
• Irrigation for first few years only -contractor installed as part of 6 month maintenance period
• Use mulch that knits together not bark that floats Valley Oak Trees
White flowering Ceanothus Rushes and Sedges
Landscape Plan
CONSTRUCTION• Demolition of parking lot
• Relocation of lights
• Restriping of parking
Construction - continued
• Excavation
• Installation of rock
• Boardwalks
• Topsoil
• Landscaping
• Irrigation
Grant from San Mateo County Storm Water Pollution Prevention
Cost – about $270,000 for design, engineering, and construction
Sustainable, Green Streets and Parking Lots program
Vehicle License Fees
Managed thru C/CAG
Financing
Interpretive Sign • Educating the public
• Staff designed sign
• Ordered from the Web
Lesson Learned: Infiltration Test• Percolation test did
not work• Infiltration test did• Works like toilet float• Three tests through
out the site
Lesson Learned continued
Erosion along edge
Gutter debris into curb extension – use rock not pea gravel
LESSONS LEARNED
Infiltration test for soil drainage
Added one foot rock strip to deter erosion
Enlarged rock storage area in swale
Include maintenance period and simple irrigation system
Check on plant availability
Contractor qualifications in specifications important
Questions and Comments
Thank you